Dialectical Behavioral Therapy (DBT) is a cognitive-behavioral treatment developed specifically for the treatment of suicidal individuals meeting criteria for Borderline Personality Disorder (BPD). Eight randomized trials and four controlled trials have been completed to date demonstrating the efficacy of DBT. A large number of trials are underway or planned. However, very few empirical studies have been conducted testing the Linehan's underlying theory of BPD on which the treatment is based. No studies have examined Linehan's principle hypothesis that improvements in emotion regulation are associated with improved clinical outcomes. Aims of this research are to: 1) develop and evaluate innovative multi-method laboratory and field measures of emotion regulation and dysregulation suitable for use in future longitudinal treatment and 3) test hypotheses generated by Linehan's theory by comparing responses on the measurement battery of suicidal BPD patients with healthy controls. We intend to examine five principle tests of emotional vulnerability and regulation given at three time points: 1) baseline emotion measures during a non-stressful task, 2) emotionally evocative films, 3) a problem-solving task paired with tasks of frustration tolerance and delay of gratification, and 4) an information processing task following a stressful task and 5) 32-hour ambulatory monitoring.